Electrical energy generator

ABSTRACT

An electrical energy generator that converts kinetic energy harvested from voluntary motor activity of a human or animal to electrical energy. The electrical energy generator includes a housing, a coil of electrically conductive material, a reciprocally movable electromagnetically active mass, springs connecting the mass to either the housing or to adjustment means engaged with said housing, and, optionally, means for constraining non-linear motion of the electromagnetically active mass, and/or means of mitigating motion retardation of the electromagnetically active mass within any existing housing atmosphere. The electrical energy generator may be associated with a carried item, such as a backpack.

TECHNICAL FIELD

A device for harvesting mechanical energy from a moving mass andconverting the harvested mechanical energy into usable electrical energyis disclosed. The device permits the capture of mechanical energyimparted to the device from movement, such as human gait activities, andthe conversion of the captured mechanical energy into electrical energy.The device may be used to provide power to a wide variety of electronicdevices.

BACKGROUND

Mechanical energy comprises a number of forms of energy including, butnot limited to kinetic energy. Mechanical energy is manifested in thebodies of humans and animals as a result of their physical processes.Such physical processes include voluntary body movements. Amongstvoluntary body movements are gait processes. Gait activities includestepping, walking, running, climbing, jumping, and similar activities.Other voluntary body movements include grasping, reaching, shaking,swinging, stretching, etc. All voluntary body movements are manifestedas motion of body members having mass so that all voluntary motoractivities develop kinetic energy. Further, voluntary motor activitiesmay impart kinetic energy to peripheral masses engaged with a movingbody.

It is sometimes desirable to convert mechanical energy to electricalenergy. An example is the conversion of kinetic energy into electricalenergy as the kinetic energy of a mass moves a magnetic field relativeto a conductive coil thereby converting the kinetic energy of the massto electrical energy by action of electromagnetic induction.

Devices to convert the kinetic energy manifested in the bodies andperipheral masses engaged with the bodies of humans as a result of theirphysical processes into electrical energy are not well-developed.Accordingly, it is desirable to provide a device to harvest kineticenergy imparted by voluntary motor activities and convert the harvestedmechanical energy into electrical energy.

SUMMARY

Provided is an electrical energy generator comprising a housing having alongitudinal axis, an interior cavity, an interior cavity surface, andan exterior surface, an electrically conductive material engaged aboutat least a portion of said exterior surface of said housing andextending along at least a portion of said longitudinal axis, anelectromagnetically active mass positioned within said housingreciprocally movable along at least a portion of said longitudinal axisand constrained within said housing to substantially preventnon-reciprocating motion of said electromagnetically active mass withinsaid housing, a first spring having first and second ends, wherein oneend is engaged with said housing and one end is engaged with saidelectromagnetically active mass, and a second spring having first andsecond ends, wherein one end is engaged with said housing and one end isengaged with said electromagnetically active mass.

According to other embodiments, additionally provided is a mechanicalenergy harvester comprising a housing having a longitudinal axis,electrically conductive material engaged about at least of portion ofthe exterior surface of said housing and extending along at least aportion of said longitudinal axis, an electromagnetically active masspositioned within said housing, said mass reciprocally movable along atleast a portion of said longitudinal axis, a first spring having firstand second ends, wherein one end is engaged with said housing and oneend in engaged with said electromagnetically active mass, a secondspring having first and second ends, wherein one end is engaged withsaid housing and one end is engaged with said electromagnetically activemass, and a means to mitigate motion retardation of saidelectromagnetically active mass within the housing.

According to further embodiments, also provided is a electrical energygenerator comprising a housing having a longitudinal axis, an interiorcavity, an interior cavity surface, and an exterior surface, anelectrically conductive material engaged about at least a portion ofsaid exterior surface of said housing and extending along at least aportion of said longitudinal axis, an electromagnetically active masspositioned within said housing reciprocally movable along at least aportion of said longitudinal axis, a first spring having first andsecond ends, wherein one of said ends is engaged with saidelectromagnetically active mass, and a second spring having first andsecond ends, wherein one of said ends is engaged with saidelectromagnetically active mass, and at least one spring deflectionadjustor engaged with said housing and at least one of said springs.

Further provided is a wearable or carryable item comprising a pack, astrap attached to said pack, and an electrical energy generator engagedwith said pack. According to illustrative embodiments the backpackcomprises a pack, a strap attached to said pack, optionally, a frameattached to said pack; and the electrical energy generator (i)positioned within said pack, (ii) engaged with said pack, (iii) engagedwith said frame, if present, or a combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one illustrative embodiment of theelectrical energy generator.

FIG. 2 is a perspective view of another illustrative embodiment of theelectrical energy generator.

DETAILED DESCRIPTION

Kinetic energy is manifested in the bodies of animals and humans, as aresult of different voluntary motor activities. Voluntary motoractivities include, for example, gait processes, leg movements, armmovements, head movements, torso movements, and the like. Kinetic energyis also manifested in the objects or masses that are moved by a human oranimal in the course of transporting them. Some voluntary motoractivities, such as human walking gait, are rhythmic activities whichhave a predictable frequency or periodicity. In the case of humanwalking gait, the predictable frequency is approximately 2 Hz.

An electrical energy generator for harvesting kinetic energy andconverting the harvested kinetic energy developed or imparted byvoluntary motor activities into electrical energy is provided. Theelectrical energy generator generally comprises a housing, an inductioncoil, an electromagnetically active mass movable in a reciprocatingmanner relative to the housing, and at least one spring engaging theelectromagnetically active mass to the housing.

According to certain illustrative embodiments, the electrical energygenerator generally comprises a housing, an induction coil, anelectromagnetically active mass movable in a reciprocating mannerrelative to the housing, a first spring engaged with the mass and thehousing, and a second spring engaged with the mass and the housing.

According to further illustrative embodiments, the electrical energygenerator comprises a housing, an induction coil, an electromagneticallyactive mass movable in a reciprocating manner relative to the housing, afirst spring engaged with the mass and the housing, a second springengaged with the mass and the housing, wherein the electromagneticallyactive mass is constrained within the housing to minimize or otherwisesubstantially prevent non-reciprocating movement of the mass.

According to other illustrative embodiments, the electrical energygenerator comprises a housing, an induction coil, an electromagneticallyactive mass movable in a reciprocating manner relative to the housing, afirst spring engaged with the mass and the housing, and a second springengaged with the mass and the housing, and means of mitigating motionretardation of the electromagnetically active mass within the housing.

According to additional illustrative embodiments, the electrical energygenerator comprises a housing, an induction coil, an electromagneticallyactive mass movable in a reciprocating manner relative to the housing, afirst spring engaged with the mass and the housing, and a second springengaged with the mass and the housing, and at least one springdeflection adjustor.

It should be noted that the electrical energy generator may include acombination of two or more of means for constraining thenon-reciprocating movement of the electromagnetically active mass withinthe housing, means for mitigating motion retardation of theelectromagnetically active mass within the housing, and at least onespring deflection adjustor.

The device harvests mechanical energy and converts the harvestedmechanical energy into electrical energy. By harvesting mechanicalenergy from the reciprocating mass and converting it into electricalenergy, the device acts as a linear electrical generator. The generatedelectrical energy may be used to power a wide variety of electronicdevices including, without limitation, locators, signaling equipment,entertainment equipment, energy storage equipment, radio receivers,radio transmitters, wireless telephones, cameras, global positioningsystem (GPS) equipment, and like electronic devices.

The housing of the device may comprise any suitable structure, capsule,container, or vessel that is capable of engaging the other components ofthe electrical energy generator. The housing general includes alongitudinal axis, an exterior surface, an interior cavity, and aninterior surface. Without limitation, according to certain embodiments,the housing comprises an elongated cylinder or tube having an interiorcavity or volume.

The housing may be constructed of any material that can support theengagement of device components and that does not interfere with theharvest of mechanical energy or conversion of the mechanical energy intoelectrical energy. Without limitation, suitable material that may beused to construct the housing of the device comprises metal, metalalloys, plastic, glass, composite materials, or combinations thereof.

The housing may be provided as an open container, such that the interiorof the housing is in communication with the external environmentsurrounding the housing. According to embodiments in which the housingis open, the means of communication with the environment surrounding thehousing may include apertures, holes, vents, slots, perforations, orlike structure located within the wall of the housing, thereby providingcommunication between the interior cavity of the housing and theexternal environment. In open embodiments, the housing atmosphere isgenerally substantially identical to the surrounding environmentalatmosphere.

According to other embodiments, the housing comprises a closed structuresuch that the interior of the housing is substantially isolated from theenvironment surrounding the housing. According to embodiments includinga closed housing, the housing atmosphere need not be substantiallyidentical to the surrounding external environmental atmosphere. Forexample, without limitation, the housing atmosphere may comprise air,nitrogen, a Nobel gas, mineral oil, vegetable oil, water, saline,substantial vacuum, a ferrofluid, or combinations thereof.

The device includes an electrically conductive material that is engagedabout at least a portion of the exterior surface of said housing.Without limitation, the electrically conductive material may be providedin the form of an induction coil. The induction coil may include anarmature, inductor, wire coil, or any other looped electricallyconductive material. A change in a local magnetic field produces acurrent within and a potential across an induction coil. Because theinduction coil is engaged about the housing and extends along a portionof the axis of the housing, a change in a magnetic field proximal tothat portion of the housing engaged with the induction coil produces acurrent within and a potential across the induction coil.

The device includes at least one spring engaging the electromagneticallyactive mass to the housing. The springs generally have opposite firstand second ends, and are engaged at one end with the housing and at theother end with the electromagnetically active mass. A spring is anycomponent which produces a restorative force in response to itsdisplacement. Certain springs produce restorative forces directlyproportional to their displacement. Springs which produce restorativeforces directly proportional to their displacement are springs whichobey Hooke's Law. A spring accumulates mechanical energy in the form ofpotential energy as work is done upon it and releases it as theabove-referenced restorative force. The relationship between therestorative force and the displacement is the spring coefficient. Insprings which obey Hooke's Law, the spring coefficient is substantiallyconstant.

According to certain illustrative embodiments, the electrical energygenerator includes first and second springs that obey Hooke's Law. Thesefirst and second springs are attached to opposite ends of the devicehousing and to opposite ends of the electromagnetically active mass thatis located within the device housing. Because these springssubstantially obey Hooke's Law, the springs are considered to beharmonic oscillators and can provide a natural frequency. In certaincircumstances, however, it may be advantageous to utilize springs thatpossess stiffening spring characteristics such that at the end oftravel, there would be no need to incorporate any rebound means with thedevice.

In certain embodiments, the springs included in the device comprise coilsprings. A coil spring is a type of torsion spring. A coil springcomprises an elastic material formed into a helix, or spiral, or spiralhelix having two opposite ends. The coil springs may comprise eithercompression springs or extension springs.

A spring pre-load is a load that exists in the spring prior todeflection of the spring from some initial state. As used herein,pre-load of a spring refers to the load in the spring in the unexciteddevice in which the electromagnetically active mass is at rest. Thedevice may also include a suitable means for adjusting the deflection orspring pre-load on the coil springs. A means of adjusting springpre-load comprises any component which introduces or removes a load,tension or compression of an installed spring, usually in the unexciteddevice. Introduction or removal of a load of an installed spring may bedone by adjusting the deflection of the spring. In certain embodimentsthe means of adjusting spring pre-load and deflection comprises amovable member with which the spring to have its pre-load and deflectionadjusted is engaged. In such embodiments, the region of engagementbetween the spring and the member is movable with respect to thehousing. In certain embodiments, the moveable member comprises athreaded member. Threaded members may comprise screws, bolts, andthreaded bushings. In certain embodiments the threaded member is engagedwith a counterpart threaded receiver that is substantially fixed to orintegral to the housing. One illustrative method of moving the point ofengagement between the spring and the threaded member with respect tothe housing is by advancement or retraction of the threaded member byrotating the threaded member with respect to the threaded receiver. Asthe threaded member is rotated, the threaded member and the region ofengagement between the spring and the member moves helically withrespect to the threaded receiver, and thereby moves helically withrespect to the housing. The amount of movement will be equal to theproduct of the thread pitch and the number of rotations made. The amountof change in the load will be equal to the product of the amount ofmovement and the spring coefficient.

In certain embodiments, the springs comprise a first spring having afirst end engaged with the housing and a second end engaged with saidelectromagnetically active mass, and a second spring having a first endengaged with the housing and a second end engaged with saidelectromagnetically active mass. In certain embodiments, the springscomprise a first spring having a first end engaged with a first threadedmember and a second end engaged with said electromagnetically activemass, and a second spring having a first end engaged with a secondthreaded member and a second end engaged with said electromagneticallyactive mass.

As used in this disclosure, “electromagnetically active” refers to amass that is capable of affecting a magnetic field. Electromagneticallyactive components include, but are not limited to, permanent magnets,electromagnets, inductors, and materials having magnetic permeability.The electrical energy generator may comprise one or moreelectromagnetically active components to affect a desired magneticfield.

An electromagnetically active mass may be any electromagnetically activecomponent which also has mass. An electromagnetically active mass iscapable of producing a magnetic field or bending the flux lines of amagnetic field. Electromagnetically active masses capable of producing amagnetic field comprise permanent magnets, electromagnets and the like.Electromagnetically active masses capable of bending the flux lines of amagnetic field may also comprise materials having magnetic permeability.In certain embodiments, the materials having magnetic permeability arematerials which have a high permeability. Without limitation, materialswhich have a high permeability comprise iron, nickel, chromium, and likematerials. In certain embodiments, an electromagnetically active massmay comprise metal, metal alloys, ceramics, and mixtures thereof.

The electromagnetically active mass is positioned within the interiorcavity of the housing and is engaged with each of two coil springs, witheach of the coil springs being further engaged with the housing. Themanner of engagement of the springs and mass allows theelectromagnetically active mass to move in a reciprocating manner withrespect to the housing. The electromagnetically active mass defines avolume which is swept out by the electromagnetically active mass as itmoves. The volume which is swept out by the electromagnetically activemass as it moves is at least a portion of the volume of the interiorcavity of the housing.

The shape of the electromagnetically active mass can vary greatly, andthere is no particular shape to which the electromagnetically activemass must be limited. In certain embodiments, the electromagneticallyactive mass comprises an axisymmetric shape. In certain embodiments, theelectromagnetically active mass comprises substantially cylindricalshape.

In certain embodiments, the electromagnetically active mass comprises atleast one through-hole. In certain embodiments the electromagneticallyactive mass is a substantially cylindrical axisymmetric mass comprisinga through-hole.

A guidance means comprises any component that comprises a portion of thehousing, or that is engaged to or integral with, the housing and has aguidance surface for the electromagnetically active mass over at least aportion of the path described by the mass as it moves. In certainembodiments, the material of the guidance means comprises metal,plastic, glass, composite materials, or combinations thereof. In certainembodiments the guidance surface of the guidance means comprises asurface coating. The surface coating may comprise metal, plastic, glass,composite materials, or combinations thereof. In certain embodiments theguidance means, or the guidance surface of the guidance means, maycomprise PTFE, PEEK, or oil-impregnated bronze. The guidance surface ofthe guidance means may substantially coincide with at least a portion ofthe surface of the volume swept out by the electromagnetically activemass as it moves. According to certain embodiments, the guidance meansguides the mass by providing restorative forces to the mass indirections substantially normal to the surface of the means in responseto contact between the mass and the means. These restorative forces arereferred to as “normal forces”. By providing such restorative forces,the guidance means impedes motion of the mass in directions normal tothe means. In certain embodiments, the mass may be engaged with theguidance means during all portions of the motion of the mass. In certainembodiments, the mass is constrained by the guidance means to minimizesubstantially all motion of the mass other than linear reciprocation,such that motion of the mass is limited to substantially linearreciprocation. There will exist a coefficient of friction determined bythe material of the guidance surface and the material of theelectromagnetically active mass which contacts the material of theguidance surface. The product of the coefficient of friction and thenormal forces defines the magnitude of friction forces between the massand the means which retard the motion of the mass. In certainembodiments, the coefficient of friction is selected to be very low inorder to minimize the magnitude of friction forces.

In certain embodiments, the guidance surface of the guidance meanscomprises the interior surface of the housing. In certain embodiments,in which the electromagnetically active mass comprises at least onethrough-hole, the guidance means comprises a shaft or rod passingthrough a through-hole and along which said electromagnetically activemass moves as it reciprocates.

The electrical energy generator may further comprises a means ofmitigating motion retardation of the electromagnetically active mass bythe housing atmosphere. The housing atmosphere comprises a fluid,wherein such fluid may be a gas or a liquid. Fluids are known to retardthe motion of materials through them. In certain circumstances, thehousing atmosphere will retard the motion of the electromagneticallyactive mass through the housing atmosphere.

One type of retardation of the motion of the electromagnetically activemass is by viscous effects. Viscous effects which retard motion appearwhenever a body moves through a fluid having a positive viscosity. Onemeans of mitigating motion retardation by viscous effects is byrarification or evacuation of the housing atmosphere. In certainembodiments, the housing atmosphere comprises a gas at sub-atmosphericpressure, such that the housing atmosphere is reduced, rarified, orevacuated to the point that it comprises a substantial vacuum.

Retardation of the motion of the electromagnetically active mass mayoccur by pressure differentials. Pressure differentials may be createdby motion of an object within, and in close clearance to, a closedhousing. In certain embodiments, the electromagnetically active mass maybe engaged in very close tolerance to a closed housing. One means ofmitigating motion retardation by pressure differentials is by theinclusion of apertures, flow-paths, flutes, or ducts to permit flow fromthe region into which the mass is moving and to the region from whichthe mass is moving. In certain embodiments, the interior surface of thehousing may comprise longitudinal flutes to permit flow of the fluidcomprising the housing atmosphere from one region of the interior cavityto another region of the interior cavity. In certain embodiments theelectromagnetically active mass may comprise one or more through-holesor flutes which permit flow of the fluid comprising the housingatmosphere around, across, or through the mass.

According to certain embodiments, the electrical energy generator mayfurther comprise an electromagnetically active shroud that is engagedwith the housing and at least partially covering the induction coil. Incertain embodiments, the electrical energy generator comprises anelectromagnetically active shroud that is engaged with the housing whichat least partially covers said housing. In certain embodiments theelectrical energy generator may comprise an electromagnetically activeshroud that is engaged with the housing which fully covers said housing.In certain embodiments the electromagnetically active shroud maycomprise a permanent magnet. In certain embodiments, theelectromagnetically active shroud comprises an unmagnetized materialhaving magnetic permeability. In embodiments in which theelectromagnetically active mass comprises an unmagnetized materialhaving magnetic permeability, the device will further comprise anelectromagnetically active shroud which comprises a permanent magnet. Incertain embodiments in which the electromagnetically active masscomprises a permanent magnet, the device comprises anelectromagnetically active shroud comprising an unmagnetized materialhaving magnetic permeability.

The electrical energy generator comprises an electromagnetically activemass which reciprocates within the housing. Exciting forces acting onthe housing excite the mass causing it to move within the housing in areciprocating manner which is substantially harmonic. Further, theelectrical energy generator comprises components which remove mechanicalenergy from the mass when it is in motion, thereby electromagneticallydamping it. Because of these properties, certain embodiments of theelectrical energy generator may be described as a substantially harmonicdamped oscillator. It should be noted that the damping of the energyfrom the mass may comprise critically damping, greater than criticallydamping or less than critically damping. According to certainillustrative embodiments, the damping of the energy from the masscomprises less than critical damping. According to yet furtherembodiments, the damping of the energy of the mass may be variable.

When a driving force is acting on the electrical energy generator,according to certain embodiments, the device behaves as a substantiallyharmonic driven, damped oscillator. Harmonic oscillators have afundamental or natural frequency which is a function of oscillating massand spring coefficient. Because the mass of the electromagneticallyactive mass is determinable and because the spring coefficient of thespring is determinable, the natural frequency of the device is alsodeterminable. The selection of the mass or spring coefficient or both toadjust the natural frequency of the device is referred to herein as“tuning”. That is, the natural frequency of the device may be tuned byselection of the mass or the spring coefficient or both.

Because the mass, by definition, has inertia, an exciting force directedto the device along a direction which is not perpendicular to the axisof reciprocation, causes the housing to be displaced to a greater extentthan the mass is caused to be displaced. This difference in displacementcauses some of the exciting kinetic energy imparted by the action of theexciting force acting over said displacement to be absorbed by theelectromagnetically active mass, the springs and the induction coil.

Because the electrical energy generator includes an electromagneticallyactive mass, a spring, and an induction coil, when set into motion, thedevice can behave as a damped vibrating system and will vibrate until itdissipates the exciting energy. The natural frequency or frequencies ofthe harvester can be predetermined. Without limitation, in certainembodiments, the electrical energy generator behaves as a substantiallyharmonic oscillator having one natural frequency. The level of dampingin the device can be predetermined.

The certain illustrative embodiments of the device will be described infurther detail with respect to the Figures. It should be noted that theelectrical energy generator should not be limited to the illustrativeembodiments depicted by the Figures.

As shown in FIG. 1, the device (110) comprises a housing (120) whichcomprises an elongated circular cross-section tube having first andsecond ends. The housing (120) comprises an internal cavity (122)defined by the tube, an interior surface (124) and an atmosphere (126).The device further comprises a first spring (130) having a first end anda second end. Spring (130) comprises an extension coil spring having thefirst end attached to the first end portion of the housing (120). Thedevice further comprises a second spring (132) having a first end and asecond end. Spring (132) comprises an extension coil spring having thefirst end attached to the first end portion of the housing (120). Thedevice (110) further comprises an electromagnetically active mass (140)engaged with each of springs 130 and 132. The electromagnetically activemass (140) is moveable within said housing (120). Theelectromagnetically active mass (140) moves in a reciprocating manneralong a path constrained by a guidance means (160), which is, in theembodiment shown, the interior surface (124) of the housing (120).Movement of electromagnetically active mass (140) relative to thehousing (120) causes motion of said mass-engaged second end of eachspring (130 and 132) with respect to said housing-engaged first end ofeach spring (130 and 132) such that the motion of theelectromagnetically active mass (140) relative to the housing (120)results in deflection of the springs (130 and 132). The device (110)further comprises an induction coil (150) that is engaged about theexterior portion of the housing (120).

As shown in FIG. 2, the device (210) comprises a housing (220) whichcomprises an elongated circular cross-section tube having a first andsecond ends. The housing (220) comprises an internal cavity (222)defined by the tube, an interior surface (224), an atmospheresubstantially similar to the ambient atmosphere (226), and apertures inthe housing which provide communication between the exterior environmentand the interior cavity (222) of housing (220). The device furthercomprises a first spring (230) having a first end and a second end.Spring (230) comprises a compression coil spring having said first endattached to the first end portion of the housing (220). The devicefurther comprises a second spring (232) having a first end and a secondend. Spring (232) comprises a compression coil spring having said firstend attached to the first end portion of the housing (220). The device(210) further comprises an electromagnetically active mass (240) engagedwith each spring (230 and 232). The electromagnetically active mass(240) is moveable within said housing (220). The mass (240) moves in areciprocating manner along a path constrained by a guidance means (260)which is, in the embodiment shown, an elongated rod engaged at eitherend with housing (220) and passing through a through-hole (242) in theelectromagnetically active mass (240). Movement of electromagneticallyactive mass (240) relative to the housing (220) causes motion of saidmass-engaged second end of each spring (230 and 232) with respect tosaid housing-engaged first end of each spring (230 and 232) such thatthe motion of the mass (240) relative to the housing (220) results indeflection of the springs (230 and 232). The harvester (210) furthercomprises an induction coil (250) engaged about the exterior surface ofthe housing (220).

In certain embodiments the mechanical energy harvester is engaged with aworn item or a carried item. Worn items comprise clothing, such as ahat, belt, shirt, pants, dress, skirt, sweater, sweatshirt, jacket andthe like. Protective gear, includes without limitation body armor, lifevest, personal flotation devices and the like. Carrying items includewithout limitation backpacks, waist-packs, field-packs, medical packs,bags, tool-bags, book-bags, purses, briefcases, holsters, sheaths andthe like.

In embodiments in which the electrical energy generator is engaged witha worn item, the worn item is excited by exciting forces imparted fromthe wearer, and the electrical energy generator is excited by excitingforces imparted from the worn item. The engagement of the electricalenergy generator with the worn item may be firm such that the device issubstantially immobile relative to the worn carrying device; flexible orsoft such that there is a great deal motion of the device relative tothe worn item; or somewhere in between.

According to certain illustrative embodiments, the electrical energygenerator is incorporated into a backpack. The backpack includes a packhaving a surface defining an interior for carrying items. The backpackalso includes means connected to the pack, such as straps, for engagingthe pack to a person. A backpack may also include a frame for the pack,said frame may be either internal or external to the pack.

Incorporation of the electrical energy generator into a backpack maytake a number of forms. In certain embodiments, the device may be placedwithin the interior of the pack of the backpack. The device may be freeto move within the interior of the pack, or may it may be attached to aportion of the interior of the pack by a suitable attachment means.Suitable attachment means comprise elastic straps, hook and loopfastener straps or patches, screws, bolts, adhesives, clips, clamps,carabineers, or combinations thereof. In certain embodiments, the deviceis removably secured within a pocket or pouch of the pack such that,while secured, it is substantially immovable with respect to the pack.In another embodiment, the device may be engaged with the exterior ofthe pack of the backpack. In such embodiments, the harvester may beattached to a portion of the exterior of the pack by any suitableattachment means. In certain embodiments, the device is permanentlysecured to the material of the pack such that it is substantiallyimmovable with respect to the pack. In another embodiment, the devicemay be engaged with the frame of the backpack. In some such embodiments,the device may be attached to the external surface of the frame by asuitable attachment means. Alternatively, the device may be attached tothe internal surface of the frame by a suitable attachment means. Incertain embodiments, the backpack frame itself acts as the housing ofthe device.

Without limitation, a electrical energy generator may be engaged with abackpack such that the device is excited by kinetic energy impartedthrough the backpack when the carrier of the backpack is walking. Inthis embodiment, some component of a typical walking stride excites thebackpack, which, in turn, excites the electrical energy generator. Incertain embodiments, energy may be converted by the device which isdeveloped as forces acting over a vertical displacement of the backpack.

Without limitation, a electrical energy generator may be a designed forhand-held usage such that the device harvester can be excited by shakingit by hand.

For purposes of illustration and without limitation, a common excitationfrequency for walking is about 2 Hz. This information may be used topredetermine an appropriate natural frequency of the electrical energygenerator. Depending upon the embodiment and desired operationalcharacteristics, it may be desirable to have one or more of the naturalfrequencies of the device similar to one or more of the operationalfrequencies of the source of the excitation kinetic energy; ordissimilar to one or more of the expected operational frequencies of thesource of the excitation kinetic energy by some predetermined amount. Incertain embodiments, one natural frequency of the device ispredetermined to correspond to the steady state harmonic motion of thegait of the human or animal by which it is carried or worn.

While the electrical energy generator has been described in connectionwith various illustrative embodiments, as shown in the Figures, it is tobe understood that other similar embodiments may be used ormodifications and additions may be made to the described embodiments forperforming the same functions. Therefore, the electrical energygenerator should not be limited to any single embodiment, but ratherconstrued in breadth and scope in accordance with the recitation of theappended claims.

1. An electrical energy generator comprising: a housing having alongitudinal axis, an interior cavity, an interior cavity surface, andan exterior surface; an electrically conductive material positionedabout at least a portion of said exterior surface of said housing andextending along at least a portion of said longitudinal axis;electromagnetically active mass positioned within said housingreciprocally movable along at least a portion of said longitudinal axisand constrained within said housing to minimize or substantially preventnon-reciprocating motion of said electromagnetically active mass withinsaid housing; a first spring having first and second ends, wherein oneof said ends is engaged with said housing and one of said ends isengaged with said electromagnetically active mass; and a second springhaving first and second ends, wherein one of said ends is engaged withsaid housing and one of said ends is engaged with saidelectromagnetically active mass.
 2. The electrical energy generator ofclaim 1, wherein said housing comprises a cylinder or tube.
 3. Theelectrical energy generator of claim 2, wherein said electricallyconductive material comprises an induction coil.
 4. The electricalenergy generator of claim 1, wherein the entirety of saidelectromagnetically active mass is adapted to pass through the entiretyof said induction coil twice during a single reciprocation period. 5.The electrical energy generator of claim 4, wherein said springscomprise coil springs.
 6. The electrical energy generator of claim 5,wherein said coil springs comprise extension springs.
 7. The electricalenergy generator of claim 5, wherein said coil springs comprisecompression springs.
 8. The electrical energy generator of claim 6,wherein said electromagnetically active mass comprises at least onepermanent magnet.
 9. The electrical energy generator of claim 8, whereinsaid electrical energy generator further comprises a shroud at leastpartially covering said induction coil, said shroud having a highmagnetic permeability.
 10. The electrical energy generator of claim 9,wherein said shroud comprises a ferromagnetic material.
 11. Theelectrical energy generator of claim 6, wherein said electrical energygenerator further comprises a shroud at least partially covering saidinduction coil, and wherein: said electromagnetically active mass doesnot comprise a permanent magnet; and said generator comprises a shroudat least partially covering said induction coil, wherein said shroudcomprises a permanent magnet.
 12. The electrical energy generator ofclaim 1, further comprising guidance means to minimize or substantiallyprevent the non-reciprocating motion of said electromagnetically activemass within said housing.
 13. The electrical energy generator of claim12 wherein said guidance means comprises said interior housing surfaceor shaft engaged with said housing and said electromagnetically activemass.
 14. The electrical energy generator of claim 8, wherein saidgenerator is in electrical connection with an electronic device.
 15. Abackpack comprising: a pack; straps attached to said pack; optionally, aframe attached to said pack; and the electrical energy generator ofclaim 1 (i) positioned within said pack, (ii) engaged with said pack,(iii) engaged with said frame, if present, or a combination thereof. 16.An electrical energy generator comprising: a housing having alongitudinal axis, an interior cavity, an interior cavity surface, andan exterior surface; an electrically conductive material engaged withsaid housing; electromagnetically active mass positioned within saidhousing reciprocally movable along at least a portion of saidlongitudinal axis and constrained within said housing to minimize orsubstantially prevent non-reciprocating motion of saidelectromagnetically active mass within said housing, wherein saidelectromagnetically active mass comprises at least one permanent magnet;a first spring having first and second ends, wherein one of said ends isengaged with said housing and one of said ends is engaged with saidelectromagnetically active mass; and a second spring having first andsecond ends, wherein one of said ends is engaged with said housing andone of said ends is engaged with said electromagnetically active mass.17. The electrical energy generator of claim 16, wherein said housingcomprises a cylinder or tube.
 18. The electrical energy generator ofclaim 17, wherein said electrically conductive material comprises aninduction coil.
 19. The electrical energy generator of claim 16, whereinthe entirety of said electromagnetically active mass is adapted to passthrough the entirety of said induction coil twice during a singlereciprocation period.
 20. The electrical energy generator of claim 18,wherein said springs comprise coil springs.
 21. The electrical energygenerator of claim 20, wherein said coil springs comprise extensionsprings.
 22. The electrical energy generator of claim 20, wherein saidcoil springs comprise compression springs.
 23. The electrical energygenerator of claim 22, wherein said electrical energy generator furthercomprises a shroud at least partially covering said induction coil, saidshroud having a high magnetic permeability.
 24. The electrical energygenerator of claim 23, wherein said shroud comprises a ferromagneticmaterial.
 25. The electrical energy generator of claim 16, furthercomprising guidance means to minimize or substantially prevent thenon-reciprocating motion of said electromagnetically active mass withinsaid housing.
 26. The electrical energy generator of claim 25, whereinsaid guidance means comprises said interior housing surface or shaftengaged with said housing and said electromagnetically active mass. 27.The electrical energy generator of claim 16, wherein said generator isin electrical connection with an electronic device.